Songs that claim Covid-19 is fake and describe the vaccines as "poison" are being actively promoted to Spotify users in playlists generated by its content recommendation engine.
Tracks found on the world's largest music streaming service explicitly encourage people not to get vaccinated and say those who do are "slaves", "sheep", and victims of Satan. Others call for an uprising, urging listeners to "fight for your life".
"They fooled the whole world with PCR testing. The thought police are patrolling. Can't you see what's unfolding?" say the lyrics of another, adding: "The whole thing ends once the people have risen."
Spotify this weekend removed several of the songs flagged to it by the Observer, which it said breached rules banning content that promotes "dangerous, false, or deceptive content about Covid-19" that may pose a threat to public health.
Before being removed, the songs could be easily found using keywords through Spotify's search tool. But they were also actively promoted to users who express interest in similar songs via automatically generated playlists, potentially bringing them to a far wider audience.
One user who played a song containing anti-vaccine lyrics was given a personalised playlist directing them to even more extreme songsOf the 50 songs in that playlist, 19 included explicit references to anti-vaccine and Covid misinformation, including claims the vaccine is being used to microchip people.
Some had references to other conspiracy theories, including claims that satanic paedophiles run the world, and that the Sandy Hook school shooting in the US, which left 26 dead, was a hoax.
Among the artists whose content was recommended to users was Edward Freeman, a rapper known as Remeece, who made headlines in the UK after touring schools blasting his anti-vaccine anthem Don't Tek Di Vaccine to pupils outside school gates. The lyrics of the song - among those that remained live on Spotify last week - repeatedly say "don't tek the damn thing" and "you mad", and describe the vaccine as "poison".
Remeece has visited primary and secondary schools in London, Cornwall and Bournemouth, according to videos posted on his Instagram feed. In December, he was filmed performing the song at a protest with Piers Corbyn, a key figure in the UK's anti-vaccine movement.
Spotify has long been aware it is hosting the rapper's content - which was first reported to Spotify by a concerned parent in November, according to emails seen by the Observer. His material remained live without any content warning last week.
The findings have stoked debate about the streaming giant's handling of misinformation, with critics calling for the platform - and other streaming services hosting similar material - to be held to the same standard as traditional social media platforms such as Facebook and Instagram.
Spotify, which has more than 180 million users, has recently faced criticism over its relationship with podcaster Joe Rogan, who it signed in an exclusive deal for a reported $100m.
Several artists including Neil Young and Joni Mitchell demanded their content be removed from Spotify in protest at Rogan's alleged role in spreading misinformation about Covid-19, and 270 US doctors, scientists, healthcare professionals and professors wrote to the platform calling Rogan "a menace to public health" for airing anti-vaccine ideology.
Guests on his podcast, The Joe Rogan Experience, have included Robert Malone, a controversial infectious-disease researcher who was involved in the development of mRNA vaccine technology but has been criticised for spreading vaccine misinformation.
In response to that criticism, Spotify deleted several episodes and published new rules telling those uploading content to avoid claiming Covid-19 is a hoax and spreading anti-vaccine misinformation. It also said it would add content advisories to podcast episodes discussing Covid-19.
However, the anti-vaccine songs, which contain lyrics in some cases far more extreme than those podcasts, did not carry a content warning. In some cases the algorithm directed listeners to content with low numbers of plays, potentially amplifying the reach of misinformation that would otherwise have had a small audience. Many of the songs had titles containing keywords such as "vaccine" and "mask", suggesting it would be easy for Spotify to locate them if it wanted to.
Imran Ahmed, chief executive of the Center for Countering Digital Hate, a group that monitors misinformation and harmful content online, said the material identified contained "unscientific, provably false misinformation" that encourages listeners to refuse vaccines that could save lives.
He said: "Spotify isn't just hosting and profiting from dangerous misinformation, its algorithm is proactively connecting disparate pieces of dangerous misinformation and packaging it up to listeners. After the Joe Rogan controversy, much was made of Spotify's supposed tough stance against Covid misinformation. It appears the opposite is true."
Spotify has previously removed other types of harmful content from its platform that was deemed to breach its policies.
In December, following an investigation by Sky News, it removed almost 150 hours of content it said violated its hateful content policy, including antisemitic, racist and white supremacist material found in podcasts.
In 2020, a BBC investigation led Spotify and other platforms including Apple Music, YouTube Music and Deezer to remove racist, antisemitic and homophobic content.
An excerpt of a Hitler speech, calls for "Aryans" to make a brand new start, and references to white power were found in songs hosted by the streaming services.
Don't Tek Di Vaccine was among the songs Spotify took down this weekend. It is yet to say if it plans to add health warnings to songs which discuss Covid-19, as it has with podcasts.
A spokesperson said: "Spotify prohibits content on the platform which promotes dangerous false, or dangerous deceptive content about Covid-19 that may cause offline harm and/or pose a direct threat to public health. When content that violates this standard is identified, the appropriate enforcement action is taken."
